Process and apparatus for separating out and removing water present in liquid fuels, especially water from diesel oil

ABSTRACT

A process for separating out and removing water present in liquid fuels, especially water from diesel oil, wherein the fuel is conveyed in a line system ( 3, 9, 13 ) which serves to supply an internal combustion engine by means of a fuel delivery pump ( 12 ), water is separated out at a filter arrangement ( 5 ) which has a collecting space ( 27 ) for collecting water which has been separated out and which is connected upstream of the suction side ( 11 ) of the fuel delivery pump ( 12 ), such that its sucking action counteracts an outflow of water from the collecting space ( 27 ), and wherein, depending on the collection of a given amount of water, the sucking action of the delivery pump ( 12 ) is negated and an outlet valve disposed at an outflow orifice ( 37 ) of the collecting space ( 27 ) for removing water is opened, is characterized in that the sucking action which counteracts the outflow of water is negated by a discharge means ( 43; 53 ), by means of which a pressure gradient which enables the discharge of water can be generated at the outflow orifice ( 37 ) of the collecting space ( 27 ) over a discharge period and with the fuel delivery pump ( 12 ) running.

The invention relates to a process for separating out and removing water present in liquid fuels, especially water from diesel oil, the fuel being conveyed in a line system which is used to supply an internal combustion engine by a fuel delivery pump, water being separated out at a filter arrangement which has a collecting space for collecting the separated water, and being connected upstream from the suction side of the fuel delivery pump so that its sucking action counteracts an outflow of water from the collecting space, and depending on the collection of a given amount of water at the filter arrangement the sucking action of the delivery pump being negated and an outlet valve located at an outflow orifice of the collecting space for removing water being opened. Moreover, the invention relates to an apparatus for executing this process.

The drainage of water, with the aforementioned measures being carried out, is conventional and especially essential when heavy diesel machinery is being operated under severe conditions of use. Thus, for example, when using heavy machinery with heavy diesel engines in less highly developed countries it is difficult to obtain fuel of Central European quality. In fact, in countries with difficult climatic conditions and poor infrastructure it must be expected that the available fuel will have significant impurities, in particular a high water content. Construction and agricultural machinery is often fueled from barrels which are stored and transported more often with little or no covering at all, so that they are exposed unprotected to the elements such as rain.

According to experience, a maximum water content in diesel oil of up to 10% can be expected, and vandalism and corrupt handling can be responsible for these high water contents.

When highly contaminated diesel oil is used, for example, in the tank of a high-performance common rail diesel engine with consumption of approx. 400 l/day, the amount of water to be drained is about 40 l/day. But for commercial filters/water separators the capacity in the water collecting tank is at most 0.5 l. In view of this prior art, this means that the operator, in order to carry out the initially mentioned conventional drainage process, must shut off the engine roughly 80 times during the workday in order to negate the suction force of the fuel delivery pump which counteracts the outflow of water from the pertinent filter arrangement, according to which the operator must open the outflow orifice of the water collecting space in order to allow the collected water to flow out. If the operator does not observe the requirements, after some time water bleeds through the filter arrangement into the injection system and thus damages it, resulting in very high maintenance costs and a correspondingly long downtime of the pertinent device.

With respect to this problem, the object of the invention is to devise a process which meets the requirements which arise in operation of internal combustion engines, in particular heavy diesel engines, to an especially satisfactory degree.

Proceeding from conventional processes of the initially mentioned type, this object is achieved according to the invention in that the sucking action which counteracts the outflow of water is negated by a discharge means by which a pressure gradient which enables outflow of water can be produced at the outflow orifice of the collecting space over a discharge interval and during current operation of the fuel delivery pump.

Because, according to the invention, the discharge process is initiated by a pressure difference which causes discharge of water via the outflow orifice being produced between the inside of the collecting space and the outside, the process according to the invention enables discharge processes to be carried out while the engine is running. Therefore discharge processes can be carried out in comparatively rapid succession and thus over comparatively short discharge intervals, without disrupting operation, during which the injection system, with the fuel delivery pump continuing to run, continues to operate with the storage volume of the injection system, therefore it is not necessary to shut down the engine.

The process according to the invention makes available the option of complete automation. It can be provided here in an especially advantageous manner that a water sensor unit which detects collection of a given amount of water and its outflow produces a signal which activates the discharge means and thus automatically initiates a discharge process. The danger that the water can bleed through due to operator error is therefore prevented.

In especially advantageous embodiments, the discharge means has control electronics which processes the signal of the water sensor unit in order to determine the discharge intervals and to produce control signals for activation of the discharge means and control of the outlet valve during the determined discharge intervals.

The pressure gradient which enables outflow of water at the outflow orifice can be produced in different ways, for example, by the discharge means having a discharge pump with a suction side which can be connected to the outflow orifice of the collecting space and which produces a pressure gradient when the discharge means is activated. This embodiment constitutes a comparatively simple procedure in which sucking of water out of the collecting space takes place as necessary while the system remains in operation, without the need for interventions or changes on the actual line system.

Alternatively, the process can be carried out such that the discharge means has a hydropneumatic accumulator with an oil side which is charged with fuel by the fuel delivery pump, and a valve means which can be actuated by the control electronics such that by means of the accumulator in the filter arrangement over a discharge interval a pressure is built up which produces the pressure gradient which is necessary for outflow of water at the outflow orifice. In this form of the process there is the advantage that an additional discharge pump is not necessary.

Advantageously, depending on the signal of a temperature sensor which detects the temperature of the separated water, the control electronics can produce a heating control signal for a heating element which is designed to protect against freezing. In this way operating reliability is ensured even in winter operation or in cold climate zones.

The subject matter of the invention is also an apparatus for carrying out the process according to the invention which has the feature of claim 7 in its entirety.

Other features of the apparatus according to the invention are specified in the dependent claims 8 to 16.

The invention is detailed below using embodiments shown in the drawings.

FIG. 1 shows a simplified operating diagram to illustrate a first embodiment of the invention;

FIG. 2 shows a representation similar to FIG. 1 for illustration of the second embodiment;

FIG. 3 shows a representation of one embodiment of the apparatus according to the invention shown partially in a longitudinal section and schematically simplified for executing the example of the process shown in FIG. 1, and

FIG. 4 shows a representation of what is shown in FIG. 3 turned 90° relative to FIG. 3.

To illustrate a first embodiment of the invention, FIG. 1 shows a schematic block diagram of the fuel supply system of a diesel engine with common rail injection. Emerging from a fuel tank I the line system has a tank line 3 which leads to the inlet 6 of a prefilter 5. The prefilter 5 with a fineness of approximately 30μ has a water separator 7. The outlet 8 of the prefilter 5 is connected to a suction line 9 which leads to the suction side 11 of a fuel delivery pump 12. Its pressure line 13 is connected to the inlet 15 of a fine filter 17 which has a fineness of approximately 2-5μ. The outlet 19 of the fine filter 17 is connected to a common rail injection system 21, from its injection nozzles designated as 23 a recirculation line 25 leading back to the tank 1.

Water which is being separated from the fuel flowing through the prefilter 5 by means of the water separator 7 collects in the bottom region of the prefilter 5 and in the collecting space 27 which adjoins its underside. Details of the fluid connection and the positional relationship between the water separator 7 and the collecting space 27 are explained below using FIGS. 3 and 4. A water sensor unit 29 which detects the height of the level of the collected water in the collecting space 27 is connected by signals to the control electronics 31. The latter processes not only the signals of the water sensor unit 29, but also those of a temperature sensor 33 which activates a heating element 35 in the collecting space 27 when a freezing temperature has been ascertained.

The collecting space 27 is connected by way of its outflow orifice 37 to the suction side 41 of the discharge pump 43 with a pressure side which leads to a capture tank 45 for the discharged water. The pump 43 can be a pump version which blocks against backflow. Alternatively, there can be a nonreturn valve 39 as the outlet valve between the outflow orifice 37 and the pump 43.

When the water sensor unit 29 detects a level in the collecting tank 27 which corresponds to a given amount of collected water and signals this to the control electronics 31, a discharge process is initiated by the control electronics 31 starting the motor of the pump 43 via the supply line 47. The intake capacity of the pump 43 is chosen such that its sucking action exceeds the sucking action of the fuel delivery pump 12 so that at the outflow orifice 37 of the collecting space a pressure gradient is produced such that the collected water flows out, i.e., is sucked out by way of the pump 43. The duration of the discharge interval over which the pump 43 remains on can be determined depending on the signal of the sensor unit 29 by operation of the pump 43 being adjusted by a certain amount when the water level drops, or can be controlled depending on time, by the pump 43 operating over a fixed time interval for each discharge process. In each instance the fuel delivery pump 12 remains in operation during the discharge processes so that the engine need not be shut down.

The example shown in FIG. 2 differs from the example shown in FIG. 1 by the use of a discharge means in the form of a pressure control means which replaces the discharge pump 43 from FIG. 1. Components which correspond to the example from FIG. 1 are designated in FIG. 2 with the same reference numbers as in FIG. 1. As is apparent from FIG. 2, the pressure line 13 of the fuel delivery pump 12 leads not only to the inlet 15 of the fine filter 17, but also to the oil side 51 of a diaphragm accumulator 53 which is charged with fuel by the operating fuel delivery pump 12. In order to initiate a discharge process, which takes place in turn as in the initially described embodiment by delivering the signal from the sensor unit 29 and by the resulting activity of the control electronics 31, a 3/2-way valve 55 which is connected upstream from the inlet 6 of the prefilter 5 in the tank line 3, and a 2/2-way valve 57 which is connected downstream from the outlet 8 of the prefilter 5, are actuated. In this connection, over the discharge interval the valve 57 is closed and the valve 55 is actuated such that the tank line 3 is blocked and the oil space 51 of the diaphragm accumulator 53 is connected to the inlet 6 of the prefilter 5 by way of a branch line 59 and the 3/2-way valve 55. At the outflow orifice 37 of the collecting space 27 the pressure gradient which presses the collected water out of the collecting space 27 which in turn travels to the capture tank 45 is formed by the pressurized volume of oil supplied to the prefilter 5 by way of the diaphragm accumulator 53. In the example shown in FIG. 2, the outlet 8 of the prefilter 5 during the discharge interval can be blocked by the valve 57. When the diaphragm accumulator 53 is charged with enough pressure and a sufficiently large volume of pressurized oil which flows via the valve 55 into the prefilter 5 is available in the oil space 51 so that a sufficient pressure rise is formed in the prefilter 5 during the discharge interval, the 2/2-way valve can be omitted. As in the first described embodiment, during the discharge interval the fuel delivery pump 12 can continue to operate, i.e., the engine need not be shut down. When the discharge interval is ended, the valve 55, optionally the valve 57, is controlled again such that flow takes place through the tank line 3 and the suction line 9, the branch line 59 is blocked again and the diaphragm accumulator 53 is again charged by way of the pressure line 13.

FIGS. 3 and 4 show one example of the apparatus according to the invention for executing the process, the apparatus being made as a retrofit system which can be attached to the underside 61 of the prefilter 5 at a later time, whose filter casing is made in the form of a spin-on filter.

As FIGS. 3 and 4 show, in the central region of the bottom on the underside 61 there is a water outlet 63 with an internal thread, to which a hollow screw 65 is screwed, whose internal holes 67 form a fluid connection between the bottom region on the underside 61 of the filter casing and a central depression 69 which is located on the upper end of a body 71 which is tightened by the hollow screw 65 on the underside 61 of the filter casing, a gasket 73 forming an edge-side seal.

The depression 69 forms the water collecting space 27 for the water which has been separated out by the water separator 7 of the prefilter 5 and which has a level in the collecting space 27 which is detected by the water sensor unit 29. Underneath the depression 69 which forms the collecting space 27 there are cavities in the body 71 for holding the control electronics 31, see FIG. 3, the discharge pump 43, see FIG. 4, and other components which are not shown.

While FIGS. 3 and 4 show the apparatus according to the invention in one embodiment which is made as a retrofit system which is suited for installation into existing systems at a later time, it goes without saying that the invention is especially suitable as original equipment for the pertinent systems.

In particular, the apparatus according to the invention together with the prefilter 5 which has a separator 7 and other system components, such as the pump 43, sensor unit 29, electronics 31, heating element and the like, can be combined in a standard housing. 

1. A process for separating out and removing water present in liquid fuels, especially water from diesel oil, the fuel being conveyed in a line system (3, 9, 13) which is used to supply an internal combustion engine by a fuel delivery pump (12), water being separated out at a filter arrangement (5) which has a collecting space (27) for collecting the separated water, and being connected upstream from the suction side (11) of the fuel delivery pump (12) so that its sucking action counteracts an outflow of water from the collecting space (27), and depending on the collection of a given amount of water the sucking action of the delivery pump (12) being negated and an outlet valve located at an outflow orifice (37) of the collecting space (27) for removing water being opened, characterized in that the sucking action which counteracts the outflow of water is negated by a discharge means (43, 53) by which a pressure gradient which enables outflow of water can be produced at the outflow orifice (37) of the collecting space (27) over a discharge interval and during current operation of the fuel delivery pump (12).
 2. The process according to claim 1, wherein a water sensor unit (29) which detects collection of a given amount of water and its outflow produces a signal which activates the discharge means (43; 53).
 3. The process according to claim 2, wherein the discharge means (43; 53) has control electronics (31) which processes the signal of the water sensor unit (29) in order to determine the discharge intervals and to produce control signals for activation of the discharge means (43; 53) and control of the outlet valve during determined time intervals.
 4. The process according to claim 3, wherein the discharge means has a discharge pump (43) with a suction side (41) which can be connected to the outflow orifice (37) of the collecting space (27) and produces a pressure gradient which enables outflow of water at the outflow orifice (37) when the discharge means is activated.
 5. The process according to claim 3, wherein the discharge means has a hydropneumatic accumulator (53) with an oil side (51) which is charged with fuel by the fuel delivery pump (12), and a valve means (55, 57) which can be actuated by the control electronics (31) such that by means of the accumulator (53) in the filter arrangement (5) a pressure is built up which produces the pressure gradient which is necessary for outflow of water at the outflow orifice (37).
 6. The process according to claim 4 or 5, wherein depending on the signal of a temperature sensor (33) which detects the temperature of the separated water, the control electronics (31) produces a heating control signal for a heating element (35) which is designed to protect against freezing.
 7. An apparatus for executing the process according to claim 1, with a filter arrangement (5) which has a water separator (7) and whose inlet (6) is connected to a fuel tank (1) and whose outlet (8) is connected to the suction side (11) of a fuel delivery pump (12) in the fuel supply line system of an internal combustion engine, the filter arrangement (5) having a collecting space (27) for collecting the separated water, which can be released through an outflow orifice (37) of the collecting space (27), characterized by a discharge means comprising a pressure control means (43; 53) by means of which over a discharge interval at the outflow orifice (37) a pressure gradient can be produced which enables outflow of water against the sucking action of the running fuel delivery pump (12), which action is present at the filter arrangement (5).
 8. The apparatus according to claim 7, wherein there are a water sensor unit (29) which detects the collection of a given amount of water, and control electronics (31) which processes the sensor signals of the sensor unit and which produces control signals for the discharge means and for control of a valve means which belongs to its pressure control means (43; 53).
 9. The apparatus according to claim 8, wherein the pressure control means has a discharge pump (43) with a suction side (41) which can be connected to the outflow orifice (37) for producing the pressure gradient which enables outflow of the water.
 10. The apparatus according to claim 8, wherein the pressure control means has a hydropneumatic accumulator, in particular a diaphragm accumulator (53), whose oil side (51) is connected to the pressure side of the fuel delivery pump (12) and can be connected to the inlet (6) of the filter arrangement (5) by way of a valve (55) of the valve means, which valve can be controlled by the control electronics.
 11. The apparatus according to claim 10, wherein the valve (55) is a 3/2-way valve via which the inlet (6) of the filter arrangement (5) can be connected in alternation to the accumulator (53) or the fuel tank (1).
 12. The apparatus according to claim 7, wherein it is made as a retrofit system which can be attached to an existing filter arrangement (5) which has a water separator (7).
 13. The apparatus according to claim 12, wherein for a filter arrangement in the form of a spin-on filter element (5) whose filter casing has a bottom-side water outlet (63) the retrofit system has a body (71) which can be attached to the bottom (61) of the casing and which has a cavity (69) which surrounds the water outlet (63) of the casing and which forms a component of the collecting space (27) which belongs to the filter arrangement (5) and has an outflow orifice (37) for the outflow of water from the collecting space (27).
 14. The apparatus according to claim 13, wherein the body (71) is fixed on the casing by a hollow screw (65) which is screwed to its water outlet (63) and which has holes (67) for forming a water passage to the cavity (69) which is used as the collecting space (27).
 15. The apparatus according to claim 14, wherein in the body (71) there are integrated the water sensor unit (29) for detecting the level of the water in the cavity (69), the control electronics (31), the valves optionally assigned to the latter, and optionally the discharge pump (43), whose suction side (41) is connected to the cavity (69) of the body (71) optionally by way of a nonreturn valve (39). 